- RT-PCR tests: “PCR” stands for “polymerase chain reaction” which is a way of amplifying the nucleic acids in your sample. According to the FDA, the polymerase chain reaction converts any virus RNA in your sample into DNA and “amplifies” it by making millions of copies of the DNA which the molecular test can then detect.
Because a PCR test can run multiple cycles of this amplification, it’s capable of detecting the virus even if there’s a low level of the viral RNA in your sample. The majority of the tests being conducted in India and worldwide are RT-PCR, which requires nasal and throat swabs and are used to directly detect the presence of the virus rather than antibodies.
- Rapid antibody tests: Antibody tests are fast, inexpensive, and can be used to gauge the extent of infection within a community. Antibody tests require a blood sample to determine whether the human body has antibodies for coronavirus. Antibodies are proteins produced by the body, and used by the immune system to identify and neutralise bacteria and viruses.
- Rapid antigen tests: It detects the virus rather than the antibodies produced by the body. The test is reliant on the amount of virus, or the viral load, in a nasal swab.
- TruNat tests: TruNat test, commonly used for detecting tuberculosis and HIV, works on the same principle as RT-PCR, but with a smaller kit, and produces faster results. ICMR recently approved TrueNat, manufactured by a Goa-based company, for screening and confirmation for Covid-19. A TrueNat machine is chip-based, small and portable, and mostly runs on batteries. It detects the virus in nasal or oral swabs. The machines are equipped to detect the RdRp enzyme found in the virus RNA.